Plasma focus as intense light source for soft x-ray microscopy

A plasma focus operating in nitrogen is developed as an x-ray source for the laboratory type x-ray microscope. The radiation has to be emitted into the ''window'' (2.33 nm--4.37 nm) with a reciprocal relative bandwidth (RRB) of λ/Δλ>200. The nearly coinciding Lyman-α line of nitrogen VII λ=2.48 nm and the second resonance line of nitrogen VI at λ=2.49 nm are chosen. For the use in the microscope the end on diameter of the source has to be about 200 μm with a spatial jitter below 100 μm. A prototype of the source has been examined in its spatial, temporal and spectral properties. The higher ionization cross sections of nitrogen compared to noble gases influences the start of the discharge. First experiments with Fresnel condenser zone plates (CZP) as a tool for plasma soft x-ray emission diagnostics are presented. Experimental results are compared with non LTE modeling of the collapse and pinch phase of the plasma focus